NAME

em - Intel(R) PRO/1000 Gigabit Ethernet adapter driver

SYNOPSIS

To compile this driver into the kernel, place the following line in your
kernel configuration file:
deviceem
Alternatively, to load the driver as a module at boot time, place the
following line in loader.conf(5):
if_em_load="YES"

DESCRIPTION

The em driver provides support for PCI Gigabit Ethernet adapters based on
the Intel 82540, 82541ER, 82541PI, 82542, 82543, 82544, 82545, 82546,
82546EB, 82546GB, 82547, 82571, 81572, 82573, and 82574 Ethernet
controller chips. The driver supports Transmit/Receive checksum offload
and Jumbo Frames on all but 82542-based adapters. Furthermore it
supports TCP segmentation offload (TSO) on all adapters but those based
on the 82543, 82544 and 82547 controller chips. For further hardware
information, see the README included with the driver.
For questions related to hardware requirements, refer to the
documentation supplied with your Intel PRO/1000 adapter. All hardware
requirements listed apply to use with FreeBSD.
Support for Jumbo Frames is provided via the interface MTU setting.
Selecting an MTU larger than 1500 bytes with the ifconfig(8) utility
configures the adapter to receive and transmit Jumbo Frames. The maximum
MTU size for Jumbo Frames is 16114.
This driver version supports VLANs. The em driver supports the following
media types:
autoselect Enables auto-negotiation for speed and duplex.
10baseT/UTP Sets 10Mbps operation. Use the mediaopt option to select
full-duplex mode.
100baseTX Sets 100Mbps operation. Use the mediaopt option to select
full-duplex mode.
1000baseSX Sets 1000Mbps operation. Only full-duplex mode is supported
at this speed.
1000baseTX Sets 1000Mbps operation. Only full-duplex mode is supported
at this speed.
The em driver supports the following media options:
full-duplex Forces full-duplex operation
half-duplex Forces half-duplex operation.
Only use mediaopt to set the driver to full-duplex. If mediaopt is not
specified, the driver defaults to half-duplex.
For more information on configuring this device, see ifconfig(8).

LOADERTUNABLES

Tunables can be set at the loader(8) prompt before booting the kernel or
stored in loader.conf(5).
hw.em.rxd
Number of receive descriptors allocated by the driver. The
default value is 256. The 82542 and 82543-based adapters can
handle up to 256 descriptors, while others can have up to 4096.
hw.em.txd
Number of transmit descriptors allocated by the driver. The
default value is 256. The 82542 and 82543-based adapters can
handle up to 256 descriptors, while others can have up to 4096.
hw.em.rx_int_delay
This value delays the generation of receive interrupts in units
of 1.024 microseconds. The default value is 0, since adapters
may hang with this feature being enabled.
hw.em.rx_abs_int_delay
If hw.em.rx_int_delay is non-zero, this tunable limits the
maximum delay in which a receive interrupt is generated.
hw.em.tx_int_delay
This value delays the generation of transmit interrupts in units
of 1.024 microseconds. The default value is 64.
hw.em.tx_abs_int_delay
If hw.em.tx_int_delay is non-zero, this tunable limits the
maximum delay in which a transmit interrupt is generated.

DIAGNOSTICS

em%d:Unabletoallocatebusresource:memory A fatal initialization
error has occurred.
em%d:Unabletoallocatebusresource:interrupt A fatal initialization
error has occurred.
em%d:watchdogtimeout--resetting The device has stopped responding to
the network, or there is a problem with the network connection (cable).

SUPPORT

For general information and support, go to the Intel support website at:
http://support.intel.com.
If an issue is identified with the released source code on the supported
kernel with a supported adapter, email the specific information related
to the issue to 〈freebsdnic@mailbox.intel.com〉.